三维疲劳裂纹扩展的可靠性分析

分析了三维裂纹扩展寿命主要影响因素及其分布形式，构造了正交设计表L49（7^8）来设计各种随机变量对裂纹扩展寿命关系的模拟组合，以这些模拟结果为学习训练样本，采用7-12-1三层BP网络仿真了各种随机因素与裂纹扩展寿命的复杂非线性关系，并研究了计算给定可靠度下扩展寿命和给定寿命下可靠度的分析方法和实现流程。扭力轴表面裂纹算例表明该方法合理可行。

Reliability Analysis of Three Dimensional Fatigue Crack Propagation

Main factors to effect fatigue crack propagation and these factors＇ distribution types are analyzed. In order to get the relation between crack propagation life and these random influence variables, orthogonal design table L49 （7^8） is used to arrange these simulation combinations. Simulating these various combinations to get crack propagation lives, we make use of these data as learning samples to train neural networks. Finally, 7-12-1 BP networks are obtained to simulate the non-linear relation between crack propagation life and these random influence variables. And these analysis method and realization flow are presented for computing crack propagation life given reliability or calculating reliability given life. The analysis method has proved reasonable and feasible by solving the surface crack propagation of a torsion bar.